How to quickly find sound assets
You can see all the sounds that are being used by the blend file by using the 'Outliner'.

Change the display mode of the 'Outliner' by changing the dropdown box from 'All Scenes' to either 'Sequence', 'Blend File' or 'Data Blocks'.



'Blend file' and 'Datablocks' each have a 'Sounds' section which lists all the sound files that are in use in the current blend file. The 'Sequence' view will only show audio files in use in the Video Sequence Editor and not in other sections of blender. 

To further filter the results in 'Sequence' view for just audio and not video or images type the extension of the audio files, in this case '.mp3' into the search box.



Each of these views only lists audio files that have been loaded into blender and not a direct way to edit the audio file.